From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH for-4.5] xen/arm: Correct the opcode for BUG_INSTR on arm32 Date: Fri, 05 Dec 2014 10:53:00 +0000 Message-ID: <54818E8C.3060004@linaro.org> References: <1417721215-32639-1-git-send-email-julien.grall@linaro.org> <20141204193434.GB6225@laptop.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XwqVT-0002Vd-LA for xen-devel@lists.xenproject.org; Fri, 05 Dec 2014 10:53:03 +0000 Received: by mail-wi0-f176.google.com with SMTP id ex7so1004500wid.3 for ; Fri, 05 Dec 2014 02:53:02 -0800 (PST) In-Reply-To: <20141204193434.GB6225@laptop.dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: xen-devel@lists.xenproject.org, tim@xen.org, ian.campbell@citrix.com, stefano.stabellini@citrix.com List-Id: xen-devel@lists.xenproject.org Hi Konrad, On 04/12/2014 19:34, Konrad Rzeszutek Wilk wrote: > On Thu, Dec 04, 2014 at 07:26:55PM +0000, Julien Grall wrote: >> A 0 was forgotten when the arm32 BUG instruction opcode has been added in commit >> 3e802c6ca1fb9a9549258c2855a57cad483f3cbd "xen/arm: Correctly support WARN_ON". >> >> This will result to use a valid instruction (mcreq 0, 3, r0, cr15, cr0, {7}), >> and inhibit usage of BUG/WARN_ON and co. >> >> Signed-off-by: Julien Grall >> >> --- >> >> Not sure, why I dropped the 0 when I implemented the patch... >> This is a bug fixed for Xen 4.5. This is only affected ARM32 where the >> BUG opcode was malformed. >> >> With the malformed opcode, the ASSERT/BUG_ON is skipped and the >> processor may execute another patch (because the compiler has optimized > > s/patch/path/ ? Yes. >> due the unreachable in both macro). >> >> The code modified is only executed when Xen is in bad state. > > Release-Acked-by: Konrad Rzeszutek Wilk Thanks! Regards, -- Julien Grall